Kx155 squelch

Jim K

Jim K

Final Approach
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Is the squelch on a kx155 adjustable by the user? The ops manuals floating around the internet have some vague language about adjusting the volume with the knob pulled out, then pushing it in to activate automatic squelch.

Mine makes noise, until I receive or transmit, at which point it's crystal clear. The noise sounds like ignition noise, and increases frequency with rpm. Turning off the alternator didn't help. I -think- it started after I had the magneto IRANed.... possible something got messed up then?

Is there anything I can do to diagnose, or just take it to the avionics shop? I don't want to spend money on a 40 year old second radio, but if it's a simple pot adjustment it would be nice to have it sorted.
 
It may not be a radio issue? Sounds like it started after the mag work?

It would be nice to swap in another kx-155 for testing. It may take a little to track one down.
 
Jim K said:
Is the squelch on a kx155 adjustable by the user? The ops manuals floating around the internet have some vague language about adjusting the volume with the knob pulled out, then pushing it in to activate automatic squelch.

Mine makes noise, until I receive or transmit, at which point it's crystal clear. The noise sounds like ignition noise, and increases frequency with rpm. Turning off the alternator didn't help. I -think- it started after I had the magneto IRANed.... possible something got messed up then?

Is there anything I can do to diagnose, or just take it to the avionics shop? I don't want to spend money on a 40 year old second radio, but if it's a simple pot adjustment it would be nice to have it sorted.
Click to expand...

What other stuff is going on? I've had a USB cigarette lighter adapter blow garbage all over my comms before.

Florescent lighting while the airplane is inside a hangar screws up everything too.
 
sourdough44 said:
It may not be a radio issue? Sounds like it started after the mag work?

It would be nice to swap in another kx-155 for testing. It may take a little to track one down.
Click to expand...
That's what I'm wondering, but i also thought maybe I'm using it wrong.

Anyone know if the 155a uses the same mounting rack/pins? Local shop definitely has a stack of those sitting around.

bnt83 said:
What other stuff is going on? I've had a USB cigarette lighter adapter blow garbage all over my comms before.

Florescent lighting while the airplane is inside a hangar screws up everything too.
Click to expand...
Yeah, I was thinking last night about the usb charger. Will definitely try pulling that.
 
You could have an rf interference issue. I helped a friend of mine who installed a new LED taxi light that caused his com to break squelch when it was turned on. Yes..the squelch on a KX155 can be adjusted, but you do not want to decrease the receiver sensitivity. If your KX155 works ok before you crank up your plane, you might try turning off your strobes, position lights, and unplug anything in your cigar lighter plug to verify no interference. If you have a field switch for your alternator or generator, try turning that off. If you hear ignition noise, you could have a break or poor connection on your ignition harness.
 
I have a spare KX155 sitting around if you want to swap it and check. You'd have to fly over though. :)
 
I suffered through this with my previous Tiger, received all sorts of RF interference messages on various boards, tried everything including removing the ELT. Avionics shop said I had unshielded wires (replaced) and needed new coax all the way back to both antennas (also replaced) ... no joy. Old guy takes a look, tells me to pull the KX155 and send it in as the squelch knob that is supposed to be push-pull only, has "a little wiggle" ... cost $175 to put in a new volume-squelch knob and case solved. I was getting intermittent squelch break through that was SUPER annoying
 
mine works perfectly, it's only the display that gets dim. apparently a common problem.
 
bnt83 said:
What other stuff is going on? I've had a USB cigarette lighter adapter blow garbage all over my comms before.
Click to expand...

This. When I first picked up my bonanza, I tried a usb charger that had a built in CO monitor. I thought the mechanic who did the prebuy screwed something up with the EDM-700 installation (he did, but thats another rant for another time). I ended up pulling the charger out and all the noise went away. a couple months ago I tried it again and it seemed to work fine. then we started having constant static on some frequencies, but when someone keyed up it was clear. we were thinking we were going to have to spend money on the radio, and I remembered the issue I had before. I tossed that charger out.
 
The other weirdness is that when we picked it up, there was terrible noise, to the extent that we wouldn't have flown it if we couldn't fix it. We started experimenting with turning things off, and eventually found that turning off the dme made it go away. When I got it home, I had the gtn750 updated so the FS510 would work, and it required an update to the integrated audio panel as well. After that the dme no longer made noise, but the kx155 started.

After another week flying it, I'm convinced the 155 needs a small internal squelch adjustment. Occasionally it will work without the noise, usually when I'm taxiing back in and it's good & warm.
 
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